Validating motion control for Level 4 autonomous trucks requires more than road testing. This talk presents a four-stage validation pipeline — software-in-the-loop, scenario-based verification, hardware-in-the-loop, and vehicle integration — organized around defect class specificity: each stage catches failures invisible to the others. We cover how scenario libraries are derived from safety analysis (FTA/FMEA) rather than ad hoc design, how HIL exposes integration defects undetectable in simulation, and how traceability supports formal release gating. We conclude with an honest assessment of industry gaps including simulation fidelity, HIL scalability, and regulatory acceptance of virtual evidence.

• How to allocate validation coverage across SIL, scenario, HIL, and vehicle stages using defect class specificity as the organizing principle
• Why organizational coordination — shared calendars, handoff criteria, dependency tracking — determines pipeline success more than tooling
• Where industry gaps remain in simulation fidelity, HIL scalability, and regulatory acceptance of virtual testing as safety evidence